Turbocharger having a meridionally divided turbine housing and a variable turbine nozzle

ABSTRACT

A turbocharger has a meridionally divided turbine housing defining a first scroll and a first nozzle, and a second scroll and a second nozzle. The first and second nozzles are divided from each other by a shroud plate mounted within the nozzle, for isolating the exhaust gas streams flowing through the two nozzles from each other. A plurality of first vanes are disposed in the first nozzle, and plurality of second vanes are disposed in the second nozzle. A nozzle ring rotatably supports a plurality of vane shafts that extend across the first and second nozzles, passing through openings in the shroud plate. A first vane and a second vane are affixed to each vane shaft. Rotation of the vane shafts causes the first vanes and the second vanes to pivot for regulating the two streams of exhaust gas flowing through the first and second nozzles.

BACKGROUND OF THE INVENTION

The present disclosure relates to turbochargers in which a turbine ofthe turbocharger is driven by exhaust gas from a reciprocating engine.The invention relates more particularly to turbine housings that aredivided into a plurality of substantially separate sections each fed bya separate exhaust system.

An exhaust gas-driven turbocharger is a device used in conjunction withan internal combustion engine for increasing the power output of theengine by compressing the air that is delivered to the air intake of theengine to be mixed with fuel and burned in the engine. A turbochargercomprises a compressor wheel mounted on one end of a shaft in acompressor housing and a turbine wheel mounted on the other end of theshaft in a turbine housing. Typically, the turbine housing is formedseparately from the compressor housing, and there is yet another centerhousing connected between the turbine and compressor housings forcontaining bearings for the shaft. The turbine housing defines agenerally annular chamber that surrounds the turbine wheel and thatreceives exhaust gas from an engine. The turbine assembly includes anozzle that leads from the chamber into the turbine wheel. The exhaustgas flows from the chamber through the nozzle to the turbine wheel andthe turbine wheel is driven by the exhaust gas. The turbine thusextracts power from the exhaust gas and drives the compressor. Thecompressor receives ambient air through an inlet of the compressorhousing and the air is compressed by the compressor wheel and is thendischarged from the housing to the engine air intake.

In multiple-piston reciprocating engines, it is known to design theexhaust system in such a manner as to take advantage of the pressurepulsation that occurs in the exhaust stream. In particular, it is knownto employ what is known as “pulse separation” wherein the cylinders ofthe engine are divided into a plurality of subgroups, and the pulsesfrom each subgroup of cylinders are substantially isolated from those ofthe other subgroups by having independent exhaust passages for eachsubgroup. To take best advantage of pulse separation, it is desired tominimize the communication or “cross talk” between the separate groupsof cylinders. Accordingly, in the case of a turbocharged engine, it isadvantageous to maintain separate exhaust passages all the way into theturbine of the turbocharger. Thus, the turbine housing into which theexhaust gases are fed is typically divided into a plurality ofsubstantially separate parts.

There are two basic ways in which turbine housings have been divided:(1) meridional division, and (2) sector division. In a meridionallydivided turbine housing, the scroll or chamber that surrounds theturbine wheel and into which the exhaust gases are fed is divided into aplurality of passages in the meridional plane such that each passageoccupies substantially a full circumference and the passages succeedeach other in the axial direction, such as shown in FIG. 4 of U.S. Pat.No. 4,027,994.

In a sector-divided turbine housing, the generally annular chamber isdivided into angular sectors each of which occupies only a part of thecircumference such that the passages succeed each other in thecircumferential direction, such as shown in FIG. 2 of U.S. Pat. No.6,260,358. The '358 patent also discloses fixed guide vanes that arepositioned just radially inwardly of the chamber and guide the flow intothe turbine wheel.

The present disclosure relates to turbochargers having a meridionallydivided turbine housing. The present disclosure also relates toturbochargers having a variable turbine nozzle.

SUMMARY OF THE DISCLOSURE

The present disclosure describes embodiments of turbochargers having avariable-nozzle turbine and also having a meridionally divided turbinehousing. In accordance with an embodiment of the invention, aturbocharger includes:

-   -   a turbine comprising a turbine housing and a turbine wheel        mounted in the turbine housing and connected to a rotatable        shaft for rotation therewith, the turbine housing defining a        meridionally divided scroll extending circumferentially and        surrounding the turbine wheel, the meridionally divided scroll        defining a first scroll extending substantially fully about the        turbine wheel and a separate second scroll extending        substantially fully about the turbine wheel;    -   the turbine housing defining a separate inlet for each of the        first and second scrolls through which separate first and second        exhaust gas streams are received;    -   a nozzle leading from the meridionally divided scroll generally        radially inwardly to the turbine wheel;    -   a compressor comprising a compressor housing and a compressor        wheel mounted in the compressor housing and connected to the        rotatable shaft for rotation therewith;    -   a center housing connected between the compressor housing and        the turbine housing and containing bearings for the shaft;    -   a generally annular nozzle ring having a first face comprising        one wall of the nozzle and axially spaced from an opposite wall        of the nozzle;    -   a shroud plate mounted within the nozzle, the shroud plate        meridionally dividing the nozzle into a first nozzle and a        second nozzle, the first nozzle receiving the first exhaust gas        stream from the first scroll, the second nozzle receiving the        second exhaust gas stream from the second scroll; and    -   a plurality of circumferentially spaced first vanes disposed in        the first nozzle and a plurality of circumferentially spaced        second vanes disposed in the second nozzle, the first and second        vanes being rotatably mounted to the nozzle ring so as to be        variable in setting angle for regulating exhaust gas flow to the        turbine wheel.

In one embodiment, the meridionally divided scroll of the turbinehousing defines a divider wall that provides separation between thefirst exhaust gas stream in the first scroll from the second exhaust gasstream in the second scroll. A radially innermost edge of the dividerwall is proximate a radially outer edge of the shroud plate, such thatthe shroud plate continues the separation between the first and secondexhaust gas streams through the nozzle.

In accordance with one embodiment, the nozzle ring defines a pluralityof circumferentially spaced bearing holes, and the variable nozzleincludes a plurality of vane shafts respectively disposed in the bearingholes and rotatable within the bearing holes about respective axes ofthe vane shafts. Each vane shaft has a first shaft portion affixed toone of the first vanes in the first nozzle and has a second shaftportion extending through an opening in the shroud plate and affixed toone of the second vanes in the second nozzle. Thus, rotation of the vaneshafts about the respective axes thereof causes the first vanes to pivotwithin the first nozzle and causes the second vanes to pivot within thesecond nozzle. Accordingly, a single actuator can be employed forpivoting both sets of vanes in simultaneous/synchronous fashion.

The second shaft portions of the vane shafts optionally can projectaxially beyond the second vanes and extend into blind shaft receptaclesdefined in the opposite wall of the nozzle. In this manner, the vanesshafts can be supported at both ends. In one embodiment, the blind shaftreceptacles are defined in an annular insert that is formed separatelyfrom the turbine housing and is disposed in an annular recess defined inthe turbine housing.

A plurality of first spacers can be disposed between the nozzle ring andthe shroud plate to govern a first axial spacing between the first faceof the nozzle ring and the shroud plate, and a plurality of secondspacers can be disposed between the shroud plate and the opposite wallof the nozzle to govern a second axial spacing between the shroud plateand the opposite wall of the nozzle.

In one embodiment, each of the first spacers includes a pin of smallerdiameter than the first spacer, the pin having a first portion thatprojects axially from one side of the first spacer toward the nozzlering, and the nozzle ring defines a plurality of first receiving holesthat respectively receive the first portions of the pins of the firstspacers.

Each pin can also include a second portion that projects axially from anopposite side of the first spacer toward the opposite wall of thenozzle, the second portions of the pins passing through pin-receivingholes in the shroud plate, and the opposite wall of the nozzle candefine a plurality of second receiving holes that respectively receiveends of the second portions of the pins of the first spacers.

In one embodiment, the second spacers comprise sleeves of greaterdiameter than the pins of the first spacers, each sleeve defining acentral bore through which a respective one of the pins of the firstspacers passes.

The opposite wall of the nozzle can be defined by an annular insert andthe turbine housing can define an annular recess in which the annularinsert is disposed. The annular insert can define the second receivingholes for the pins.

In one embodiment, the second receiving holes pass entirely through anaxial thickness of the annular insert and the turbine housing defines aplurality of blind holes that align with the second receiving holes andthat receive terminal ends of the second portions of the pins.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described the present disclosure in general terms, reference willnow be made to the accompanying drawing(s), which are not necessarilydrawn to scale, and wherein:

FIG. 1 is an axial cross-sectional view of a turbocharger in accordancewith one embodiment of the present invention;

FIG. 2 is a portion of FIG. 1, magnified to illustrate a variable nozzleof the turbocharger;

FIG. 3 is a sectioned view along line 3-3 in FIG. 2;

FIG. 4 is a sectioned view along line 4-4 in FIG. 3;

FIG. 5 is an isometric view of the turbine of the turbocharger in FIG.1, with the turbine housing and its annular insert removed so that thevariable nozzle is visible;

FIG. 6 is an isometric view of the variable nozzle, with the nozzle ringand the annular turbine housing insert removed in order to show detailsof the variable nozzle; and

FIG. 7 is an isometric view of the variable nozzle with the nozzle ring,the annular insert, and the shroud plate removed in order to showdetails of the variable nozzle.

DETAILED DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described in fuller detail withreference to the above-described drawings, which depict some but not allembodiments of the invention(s) to which the present disclosurepertains. These inventions may be embodied in various forms, includingforms not expressly described herein, and should not be construed aslimited to the particular exemplary embodiments described herein. In thefollowing description, like numbers refer to like elements throughout.

The present invention pertains to turbochargers that include avariable-nozzle turbine (VNT), wherein the variable nozzle comprises anarray of pivotable vanes whose setting angles can be varied forregulating flow of exhaust gas into the turbine wheel. FIG. 1illustrates a VNT turbocharger 10 in accordance with one embodiment ofthe invention. The turbocharger includes a compressor wheel or impeller14 disposed in a compressor housing 16 and mounted on one end of arotatable shaft 18. The shaft is supported in bearings 19 mounted in acenter housing 20 of the turbocharger. The shaft 18 is rotated by aturbine wheel 22 mounted on the other end of the shaft 18 from thecompressor wheel, thereby rotatably driving the compressor wheel, whichcompresses air drawn in through the compressor inlet and delivers thecompressed air to a volute 17, which collects the compressed air forsupply to the intake of an internal combustion engine (not shown) forboosting the performance of the engine.

The turbocharger also includes a turbine housing 24 that houses theturbine wheel 22. As previously noted, in reciprocating internalcombustion engines having a plurality of cylinders, it is advantageousto design the exhaust system in such a manner as to take advantage ofthe pressure pulsation that occurs in the exhaust streams dischargedfrom the cylinders. In particular, it is advantageous to employ what isknown as “pulse separation” wherein the cylinders of the engine aredivided into a plurality of subgroups, and the pulses from each subgroupof cylinders are substantially isolated from those of the othersubgroups by having independent exhaust passages for each subgroup. Totake best advantage of pulse separation, it is desired to minimize thecommunication or “cross talk” between the separate groups of cylinders.Accordingly, in the case of a turbocharged engine, it is advantageous tomaintain separate exhaust passages all the way into the turbine of theturbocharger. The turbine housing 24 in accordance with the presentembodiment of the invention therefore defines a meridionally dividedscroll 26 that surrounds the turbine wheel and that receives exhaust gasfrom the internal combustion engine for driving the turbine wheel. Inparticular, the turbine housing defines the scroll as two completelyseparate first and second scrolls 26 a and 26 b, respectively, each ofwhich extends substantially 360 degrees about the turbine wheel 22. Theturbine housing includes a divider wall 24 d that divides the scrollinto the two separate scrolls. The turbine housing also includes twoseparate exhaust gas inlets to the meridionally divided scroll, oneinlet directing a first exhaust gas stream from a first bank of internalcombustion engine cylinders (not shown) into the first scroll 26 a, andthe other inlet directing a second exhaust gas stream from a second bankof cylinders (not shown) into the second scroll 26 b. The two separateexhaust gas streams are directed from their respective scrolls 26 a and26 b generally radially inwardly through a turbine nozzle 28 to theturbine wheel 22. As the exhaust gas flows through the passages betweenthe blades of the turbine wheel, the gas is expanded to a lowerpressure, and the gas discharged from the wheel exits the turbinehousing through a generally axial bore 32 therein.

In accordance with the present embodiment of the invention, the turbinenozzle 28 is a variable nozzle for varying the cross-sectional flow areaand flow direction through the nozzle so as to regulate flow into theturbine wheel. The variable nozzle in accordance with the presentinvention advantageously preserves the separation between the twoexhaust gas streams substantially all the way until the exhaust gasstreams impinge on the turbine wheel 22.

Referring now to FIG. 2, this separation of exhaust streams in thenozzle 28 is accomplished by the provision of a shroud plate SPcomprising an annular plate that is disposed within the turbine nozzle28, with a central axis of the shroud plate being coaxial with therotation axis of the turbine wheel 22. In accordance with theillustrated embodiment of the invention, the variable nozzle 28 isdefined between an annular nozzle ring 38 mounted within the turbinehousing 24 and an opposite wall formed by an annular insert 24 i that isdisposed in an annular recess 24 r defined in the turbine housing. Theshroud plate SP divides the turbine nozzle into a first nozzle 28 a anda second nozzle 28 b. The first nozzle 28 a receives the first exhaustgas stream from the first scroll 26 a and directs the gas into theturbine wheel; similarly, the second nozzle 28 b receives the secondexhaust gas stream from the second scroll 26 b and directs the gas intothe turbine wheel. The radially outer periphery of the shroud plate SPis as close as practicable to the radially inner edge of the scrolldividing wall 24 d. The radially inner periphery of the shroud plate isas close as practicable to the turbine wheel 22, so as to maintain theseparation between the two exhaust gas streams substantially all the wayto the turbine wheel.

The variable nozzle includes a plurality of first vanes 34 a that arelocated adjacent a first face of the nozzle ring 38 and arecircumferentially spaced about the first nozzle 28 a. The variablenozzle further includes a plurality of second vanes 34 b that arecircumferentially spaced about the second nozzle 28 b. Each first vane34 a is affixed to a first portion of a vane shaft 36 that passesthrough a bearing hole 39 in the generally annular nozzle ring 38. Eachvane shaft 36 is rotatable in its bearing hole about its axis forrotating the attached vane. The first portion of each of the vane shafts36 has a vane arm 40 affixed to an end of the vane shaft that protrudesout from the second face of the nozzle ring 38, and is engaged by agenerally annular unison ring 42 (also referred to as an actuator ring)that is rotatable about its axis and that is coaxial with the nozzlering 38. An actuator (not shown) is connected to the unison ring 42 forrotating it about its axis. When the unison ring is rotated, the vanearms 40 are rotated to cause the vane shafts 36 to rotate about theiraxes, thereby rotating the first vanes 34 a so as to vary thecross-sectional flow area and flow direction through the first nozzle 28a.

As shown in FIG. 2, the second nozzle 28 b includes second vanes 34 b.In the illustrated embodiment, each vane shaft 36 has a second shaftportion that extends through an opening in the shroud plate SP and isaffixed to one of the second vanes 34 b in the second nozzle. Thus,rotation of the vane shafts 36 about the respective axes thereof causesthe first vanes 34 a to pivot within the first nozzle 28 a and causesthe second vanes 34 b to pivot within the second nozzle 28 b in asimultaneous or synchronous fashion. A single actuator (not shown) isable to pivot both sets of vanes.

In the illustrated embodiment of the invention, the second shaftportions of the vane shafts 36 project axially beyond the second vanes34 b and extend into blind shaft receptacles 44 defined in the oppositewall of the nozzle. In this manner, the vane shafts are supported atboth ends. As shown, the blind shaft receptacles can be defined in theannular insert 24 i that is formed separately from the turbine housingand is disposed in the annular recess 24 r defined in the turbinehousing. Alternatively, in another embodiment (not shown), the nozzlewall formed by the annular insert 24 i can be formed instead by anintegral part of the turbine housing 24, in which case the shaftreceptacles 44 can be defined in the turbine housing.

With reference to FIGS. 4 through 6, the variable nozzle in accordancewith the illustrated embodiment of the invention includes a plurality offirst spacers 50 a disposed between the nozzle ring 38 and the shroudplate SP to govern a first axial spacing between the first face of thenozzle ring and the shroud plate. Each of the first spacers 50 aincludes a pin 52 of smaller diameter than the first spacer. The pin hasa first portion that projects axially from one side of the first spacertoward the nozzle ring 38. The nozzle ring defines a plurality of firstreceiving holes 53 that respectively receive the first portions of thepins 52 of the first spacers.

The variable nozzle also includes a plurality of second spacers 50 bdisposed between the shroud plate SP and the opposite wall of the nozzleto govern a second axial spacing between the shroud plate and theopposite wall of the nozzle. In the illustrated embodiment, the oppositewall of the nozzle is formed by the insert 24 i. Each pin 52 alsoincludes a second portion that projects axially from an opposite side ofthe first spacer 50 a toward the insert 24 i. The second portions of thepins 52 pass through pin-receiving holes in the shroud plate, and theinsert 24 i defines a plurality of second receiving holes 54 thatrespectively receive ends of the second portions of the pins of thefirst spacers. In the illustrated embodiment, the second spacers 50 bcomprise sleeves of greater diameter than the pins 52 of the firstspacers, each sleeve defining a central bore through which a respectiveone of the pins 52 of the first spacers passes.

In the illustrated embodiment, the second receiving holes 54 passentirely through an axial thickness of the annular insert 24 i and theturbine housing 24 defines a plurality of blind holes 56 that align withthe second receiving holes 54 and that receive terminal ends of thesecond portions of the pins 52.

In the illustrated embodiment, the openings in the shroud plate for thevane shafts 36 comprise slots 37 that extend all the way to the radiallyinner periphery of the shroud plate SP, as shown in FIG. 3.Advantageously, each vane shaft 36 and its associated first vane 34 aand second vane 34 b comprise an integral one-piece construction, andthe axial spacing between the first and second vanes is slightly greaterthan the thickness of the shroud plate. Referring to FIGS. 3 and 4, theslots 37 then facilitate assembly of the variable nozzle by allowing theportions of the vane shafts 36 between the first and second vanes to beinserted into the open ends of the slots 37 and to be slid radiallyoutwardly to the closed ends of the slots, with the first and secondvanes 34 a,b disposed on opposite sides of the shroud plate. The pins 52for the first spacers 50 a are inserted through the pin-receivingopenings in the shroud plate and the second spacers 50 b are sleevedover the pins. The first portions of the vane shafts 36 can then beinserted into the bearing holes 39 in the nozzle ring 38 (FIG. 2), andthe spacer pins 52 can be inserted into the first receiving holes 53 inthe nozzle ring (FIG. 4). The second portions of the vane shafts 36 canbe inserted into the blind shaft receptacles 44 in the insert 24 i,while simultaneously inserting the spacer pins 52 through the secondreceiving holes 54 in the insert 24 i. This partial assembly can then beassembled with the turbine housing 24 by installing the insert 24 i intothe recess 24 r in the turbine housing, ensuring that the ends of thespacer pins 52 projecting from the opposite side of the insert 24 i fitinto the blind holes 56 in the turbine housing 24 (FIG. 4). The ends ofthe vane shafts 36 that protrude from the opposite side of the nozzlering 38 can then be affixed to the vane arms 40 (FIG. 7), and the unisonring 42 can be engaged with the vane arms to complete the assembly ofthe variable nozzle.

Persons skilled in the art, on the basis of the present disclosure, willrecognize that modifications and other embodiments of the inventionsdescribed herein can be made without departing from the inventiveconcepts described herein. For example, while the illustrated embodimenthas first and second nozzles 28 a and 28 b of equal axial width,alternatively the two nozzles can have different widths. Additionally oralternatively, while the first vanes 34 a are illustrated as havingidentical configurations as the second vanes 34 b, instead the firstvanes can be different in configuration from the second vanes, such ashaving different airfoil shapes and/or different setting angles. Othervariations are also possible in the practice of the invention. Specificterms used herein are employed for explanatory purposes rather thanpurposes of limitation. Accordingly, the inventions are not to belimited to the specific embodiments disclosed, and modifications andother embodiments are intended to be included within the scope of theappended claims.

What is claimed is:
 1. A turbocharger having a meridionally dividedvariable-nozzle turbine, comprising: a turbine comprising a turbinehousing and a turbine wheel mounted in the turbine housing and connectedto a rotatable shaft for rotation therewith, the turbine housingdefining a meridionally divided scroll extending circumferentially andsurrounding the turbine wheel, the meridionally divided scroll defininga first scroll extending substantially fully about the turbine wheel anda separate second scroll extending substantially fully about the turbinewheel; the turbine housing defining a separate inlet for each of thefirst and second scrolls through which separate first and second exhaustgas streams are received; a nozzle leading from the meridionally dividedscroll generally radially inwardly to the turbine wheel; a compressorcomprising a compressor housing and a compressor wheel mounted in thecompressor housing and connected to the rotatable shaft for rotationtherewith; a center housing connected between the compressor housing andthe turbine housing and containing bearings for the shaft; a generallyannular nozzle ring having a first face that comprises one wall of thenozzle and that is axially spaced from an opposite wall of the nozzle; ashroud plate mounted within the nozzle, the shroud plate meridionallydividing the nozzle into a first nozzle and a second nozzle, the firstnozzle receiving the first exhaust gas stream from the first scroll, thesecond nozzle receiving the second exhaust gas stream from the secondscroll; and a plurality of circumferentially spaced first vanes disposedin the first nozzle and a plurality of circumferentially spaced secondvanes disposed in the second nozzle, the first and second vanes beingrotatably mounted to the nozzle ring so as to be variable in settingangle for regulating exhaust gas flow to the turbine wheel.
 2. Theturbocharger of claim 1, wherein the meridionally divided scroll of theturbine housing defines a divider wall that provides separation betweenthe first exhaust gas stream in the first scroll from the second exhaustgas stream in the second scroll, and wherein a radially innermost edgeof the divider wall is proximate a radially outer edge of the shroudplate, such that the shroud plate continues the separation between thefirst and second exhaust gas streams through the nozzle.
 3. Theturbocharger of claim 1, wherein the nozzle ring defines a plurality ofcircumferentially spaced bearing holes, and further comprising aplurality of vane shafts respectively disposed in the bearing holes androtatable within the bearing holes about respective axes of the vaneshafts, each of the vane shafts having a first shaft portion affixed toone of the first vanes in the first nozzle and having a second shaftportion extending through an opening in the shroud plate and affixed toone of the second vanes in the second nozzle, such that rotation of thevane shafts about the respective axes thereof causes the first vanes topivot within the first nozzle and causes the second vanes to pivotwithin the second nozzle.
 4. The turbocharger of claim 3, wherein thesecond shaft portions of the vane shafts project axially beyond thesecond vanes and extend into blind shaft receptacles defined in theopposite wall of the nozzle.
 5. The turbocharger of claim 4, wherein theblind shaft receptacles are defined in an annular insert that is formedseparately from the turbine housing and is disposed in an annular recessdefined in the turbine housing.
 6. The turbocharger of claim 1, furthercomprising a plurality of first spacers disposed between the nozzle ringand the shroud plate to govern a first axial spacing between the firstface of the nozzle ring and the shroud plate, and a plurality of secondspacers disposed between the shroud plate and the opposite wall of thenozzle to govern a second axial spacing between the shroud plate and theopposite wall of the nozzle.
 7. The turbocharger of claim 6, whereineach of the first spacers includes a pin of smaller diameter than thefirst spacer, the pin having a first portion that projects axially fromone side of the first spacer toward the nozzle ring, and wherein thenozzle ring defines a plurality of first receiving holes thatrespectively receive the first portions of the pins of the firstspacers.
 8. The turbocharger of claim 7, wherein each pin also includesa second portion that projects axially from an opposite side of thefirst spacer toward the opposite wall of the nozzle, the second portionsof the pins passing through pin-receiving holes in the shroud plate, andwherein the opposite wall of the nozzle defines a plurality of secondreceiving holes that respectively receive ends of the second portions ofthe pins of the first spacers.
 9. The turbocharger of claim 8, whereinthe second spacers comprise sleeves of greater diameter than the pins ofthe first spacers, each of the sleeves defining a central bore throughwhich a respective one of the pins of the first spacers passes.
 10. Theturbocharger of claim 8, wherein the opposite wall of the nozzle isdefined by an annular insert and the turbine housing defines an annularrecess in which the annular insert is disposed, and wherein the annularinsert defines the second receiving holes for the pins.
 11. Theturbocharger of claim 10, wherein the second receiving holes passentirely through an axial thickness of the annular insert and whereinthe turbine housing defines a plurality of blind holes that align withthe second receiving holes and that receive terminal ends of the secondportions of the pins.